The aims of our participation in the Childrens Cancer Group are 1) to continue our excellent record of patient accrual and data acquisition for therapeutic and biologic studies; 2) to continue to expand our scientific leadership role in our areas of greatest strength, including molecular biology, neuroblastoma, brain tumors, myelodysplasias and high risk leukemias, supportive care, germ cell tumors, hepatoblastomas, and lymphomas; 3) pilot new innovative therapeutic studies for the CCG, particularly in brain tumors, neuroblastoma, and bone marrow transplantation. Patient accrual from UCSF and affiliates has tripled in the past five years, and we are one of the leading contributors to group biology and therapeutic studies. Our scientific leadership is shown by membership on 5 disease strategy groups, and members of our group are chair or co-chair of 4 discipline and strategy committees and 13 study protocols. Overall, we hold 63 appointments on CCG committees. We are conducting important pilot studies for the group, including dose-intensive continuous infusion chemotherapy for neuroblastoma, which formed the basis for two current group-wide studies, pilot studies of 131I-MIBG with and without autologous bone marrow infusion, and multiple brain tumor pilots, including interferon with hyperfractionated radiation, radiosensitizers, and chemotherapy studies. A new biology study in myelodysplasia is proposed by two of our members and we have provided complete supportive care guidelines for the Group and continue to contribute in this area. Our strong biology research laboratories in brain tumors, lymphomas, and myeloproliferative disorders are conducting multiple biology studies in the Group and providing new information for future studies.